The present invention relates to methods and apparatus for testing the battery charging systems of vehicles, such as automotive vehicles and, in particular, to systems for testing alternators while connected to the battery in the vehicle.
A number of devices have been used for testing the quality and quantity of an alternator's output. These devices typically involve loading the battery, while monitoring the alternator output. For this purpose, prior devices have use variable-load carbon piles, single fixed loads and the vehicle's own electrical accessories to increase the load on the charging system. However, each of these prior techniques has disadvantages. Carbon pile loads tend to degrade over time. Single fixed load systems cannot reliably determine the true maximum output of the alternator, because the results obtained from the single fixed load tester will vary greatly depending on the state of the charge of the battery and the size of the alternator under test. The vehicle's own electrical accessories do not create a sufficient load for effective alternator testing.